Taxonomy Metadata Attributes


Airspace Class

Preferred Label: Airspace Class
Alternative Label: Airspace Classification
Definition: A portion of airspace defined according to the complexity or density of aircraft movements, nature of the operations conducted within the airspace, the level of safety required, and national and public interest.
Narrower: Class F Airspace
Narrower: Class G Airspace
Narrower: Special Use Airspace
Narrower: Class A Airspace
Narrower: Class B Airspace
Narrower: Class C Airspace
Narrower: Class D Airspace
Narrower: Class E Airspace

Class A Airspace

Preferred Label: Class A Airspace
Definition: Class A Airspace is from 18,000 feet Mean Sea Level (MSL) up to and including Flight Level (FL) 600. This includes airspace up to 12 nautical miles off the coast of the contiguous United States and Alaska. Any space beyond the 12 nautical miles off the coast line is considered international airspace. Domestic radio navigational signal and ATC radar coverage is required to be considered Class A airspace.

Class B Airspace

Preferred Label: Class B Airspace
Definition: Class B Airspace is bounded from the surface to 18,000 feet MSL surrounding major airports. The volume of airspace for Class B is designed based on the surface area of the airport and the volume of terminal airspace controlled by the airport or terminal air traffic control center. All aircraft require ATC clearance to operate within this airspace. ATC manages separation of aircraft. VFR operation may be flown if a cloud clearance is provided by ATC.

Class C Airspace

Preferred Label: Class C Airspace
Definition: Class C airspace is bounded from the surface of the airport to 4,000 feet MSL. The first layer of the airspace is from the surface area to the ceiling boundary with 5 nautical miles radius. The second layer is from 1,200 feet MSL to the ceiling at a 10 mile radius. The outer layer extends to 20 nautical miles radius. Class C airspace surrounds airports containing regular commercial traffic of 100 passengers per flight or more. Class C airspaces contain an operational tower, radar-controlled approach system, and a minimum number of IFR approaches per year.

Class D Airspace

Preferred Label: Class D Airspace
Definition: Class D airspace is bounded from the surface of an airport to 2,500 feet MSL. The outer boundary radius varies but is typically 4 nautical miles. Class D airspace is classified as any airport with a functional control tower with minimal IFR approaches. The airspace reverts to Class E or G during hours when the tower is closed or under special conditions.

Class E Airspace

Preferred Label: Class E Airspace
Definition: Class E airspace is controlled airspace that is neither A, B, C, or D. this airspace extends from 1,200 feet Above Ground Level (AGL) up to 18,000 feet MSL. Some areas as low as 700 AGL are included and are notated in sectional charts. Most of the airspace in the United States is class E.

Class F Airspace

Preferred Label: Class F Airspace
Definition: Class F airspace is not used in the U.S. In Canada, Class F airspace is equivalent to the U.S. term, Special Use Airspace (SUA). ICAO defines Class F airspace as a hybrid of Class E and G airspace in which ATC separation guidance is available but not required for IFR operation.

Class G Airspace

Preferred Label: Class G Airspace
Definition: Class G airspace includes all airspace below 14,500 feet MSL which is not otherwise classified or controlled. Class G airspace is considered uncontrolled airspace. This work is influenced by the OGC ISO/TC211 and GeoRSS ( This document describes examples in which RDF syntax is used for Geo and FOAF vocabularies, GML syntax for gml points, and geo-coding with RSS 1.0.

Special Use Airspace

Preferred Label: Special Use Airspace
Alternative Label: SUA
Definition: Special Use Airspace (SUA) or special area of operation (SAO) is the designation for airspace in which certain activities must be confined, or where limitations may be imposed on aircraft operations that are not part of those activities.